Expanded lightweight aggregate made from glass or pumice

ABSTRACT

An expanded lightweight aggregate has compositional ranges (Wt. % Range) of about: (a) 40 to 60% ground glass or pumice, 40 to 60% water, 3 to 15% sodium silicate, and 0.1 to 5% NaNO 3  for the slurry; and (b) 50 to 85% ground glass or pumice, and 15 to 50% slurry for the granulator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No. 14/785,987 filed Oct. 21, 2015, now U.S. Pat. No. 9,475,732, which is a National Stage of International Application No. PCT/US2014/035313 filed on Apr. 24, 2014, which claims priority to U.S. Provisional Patent Application Ser. No. 61/815,328 filed on Apr. 24, 2013, and U.S. Provisional Patent Application Ser. No. 61/815,332 filed on Apr. 24, 2013. The contents of both applications are hereby incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates in general to aggregate materials, and more particularly to expanded lightweight aggregate materials made from glass or pumice.

BACKGROUND OF THE INVENTION

Lightweight aggregate materials have many uses.

SUMMARY OF THE INVENTION

The present invention provides an expanded lightweight aggregate having compositional ranges (Wt. % Range) of about: (a) 40 to 60% ground glass or pumice, 40 to 60% water, 3 to 15% sodium silicate, and 0.1 to 5% NaNO₃ for the slurry; and (b) 50 to 85% ground glass or pumice, and 15 to 50% slurry for the granulator.

The present invention also provides a method of making an expanded lightweight aggregate from glass or pumice by the following steps: (1) mixing a ground glass or pumice in the range of about 40 to 60% by weight percent with water in the range of about 40 to 60% by weight percent to produce a slurry; (2) adding a sodium silicate in the range of about 3 to 15% by weight percent to the slurry; (3) adding a NaNO₃ in the range of about 0.1 to 5% to the slurry; (4) forming aggregates in a granulator by feeding the ground glass or pumice in the range of about 50 to 85% by weight percent with the slurry in the range of about 15 to 50% by weight percent; (5) drying the formed aggregates; (6) heating the dried aggregates together with finely ground kaolin to a temperature of about 800 to 1400 degrees Celsius; and (7) cooling the heated aggregates.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures and in which:

Not applicable.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a”, “an,” and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as outlined in the claims.

The lightweight expanded glass or pumice aggregate can be made as follows:

1) Grind glass or pumice in a ball mill to produce ground material predominantly less than about 100 microns.

2) Mix the ground material with about 45-50% water to produce a slurry.

3) Add about 6-7% sodium silicate (substitution ratio of 2.5) to the slurry.

4) Add about 1% sodium nitrate (NaNO₃) to the slurry. This later acts as a blowing agent.

5) Aggregates are produced in conventional granulator by feeding about 1 part mixed slurry to 2.5 parts of ground glass or pumice. By varying the amount of water in the slurry and the ratio of ground glass or pumice to the slurry, the aggregate size can be tailored to set a maximum final aggregate size.

6) Following, the formed aggregates are dried in a conventional rotary drier.

7) Following, the dried aggregates together with about 30% finely ground kaolin are fed in to a rotary kiln where it is heated between about 800-1400 degrees Celsius, during which process the granules expand to its final size of about 0-8 mm diameter and forms the light weight expanded aggregate.

8) Upon exiting the rotary kiln as last steps the aggregates are cooled and then sieved to divide the aggregate into different end use size ranges such as 0-2 mm, 2-4 mm and 4-8 mm.

9) Alternatively finer aggregates can be formed by following the granulator, feeding the finer aggregates directly in to a flash drier that heat the material above about 800 degrees Celsius and creates expanded aggregates in the size of about 0-1 mm.

The finished lightweight expanded glass or pumice aggregate has a diameter of about 0-8 mm, a bulk density of about 0.10-0.50 g/cm3 and an effective density of about 0.10-0.8 g/cm3. The aggregates further have a compressive strength of about 0.5-5 MPa and are very good heat insulators with heat conductance of about 0.04-0.15 W/mK.

In one embodiment of the present invention, the compositional ranges of the expanded lightweight glass or pumice aggregate can be:

Component Wt. % Range Slurry: Ground glass or pumice 40-60 Water 40-60 Sodium silicate  3-15 NaNO₃ 0.1-5  For granulator: Ground glass or pumice 50-85 Slurry 15-50

For the slurry, the ground glass or pumice can be about 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60% by weight or other incremental percentage between.

For the slurry, the water can be about 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60% by weight or other incremental percentage between.

For the slurry, the sodium silicate can be about 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% by weight or other incremental percentage between.

For the slurry, the NaNO₃ can be about 0.1%, 0.2%, 0.3%, 0.4, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4% or 5% by weight or other incremental percentage between.

For the granulator, the ground glass or pumice can be about 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84% or 85% by weight or other incremental percentage between.

For the granulator, the slurry can be about 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50% by weight or other incremental percentage between.

In another embodiment of the present invention the compositional ranges of the expanded lightweight glass or pumice aggregate can be:

Component Wt. % Range Slurry: Ground glass or pumice 40-60 Water 45-50 Sodium silicate 6-7 NaNO₃ 0.9-1.1 For granulator: 1 part slurry to 2.5 parts ground glass or pumice

For the slurry, the ground glass or pumice can be about 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59% or 60% by weight or other incremental percentage between.

For the slurry, the water can be about 45%, 46%, 47%, 48%, 49% or 50% by weight or other incremental percentage between.

For the slurry, the sodium silicate can be about 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9% or 7.0% by weight or other incremental percentage between.

For the slurry, the NaNO₃ can be about 0.9%, 1.0% or 1.1% by weight or other incremental percentage between.

It may be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

All publications, patents and patent applications mentioned in the specification are indicative of the level of skill of those skilled in the art to which this invention pertains. All publications, patents and patent applications are herein incorporated by reference to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference.

The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.

As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

All of the compositions and/or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it may be apparent to those of skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims. 

What is claimed is:
 1. An expanded lightweight aggregate formed from a mixture comprising: a first ground pumice in the range of about 40 to 60% by weight percent for a slurry; a water in the range of about 40 to 60% by weight percent for the slurry; a sodium silicate in the range of about 3 to 15% by weight percent for the slurry; a NaNO₃ in the range of about 0.1 to 5% for the slurry; a second ground pumice in the range of about 50 to 85% by weight percent for a granulator; and the slurry in the range of about 15 to 50% by weight percent for the granulator.
 2. The expanded lightweight aggregate as recited in claim 1, wherein the water is in the range of about 45 to 50% by weight percent for the slurry.
 3. The expanded lightweight aggregate as recited in claim 1, wherein the sodium silicate is in the range of about 6 to 7% by weight percent.
 4. The expanded lightweight aggregate as recited in claim 1, wherein the NaNO₃ is in the range of about 0.9 to 1.1% by weight percent.
 5. The expanded lightweight aggregate as recited in claim 1, wherein the granulator has a ratio of about 1 part of the slurry to about 2.5 parts of the second ground pumice.
 6. The expanded lightweight aggregate as recited in claim 1, wherein the expanded lightweight aggregate has a bulk density in the range of about 0.10 to 0.5 g/cm³ and an effective density in the range of about 0.10 to 0.8 g/cm³.
 7. The expanded lightweight aggregate as recited in claim 1, wherein the expanded lightweight aggregate has a compressive strength in the range of about 0.5 MPa to 5 MPa.
 8. The expanded lightweight aggregate as recited in claim 1, wherein the expanded lightweight aggregate has a heat conductance in the range of about 0.04 to 0.15 W/mK.
 9. The expanded lightweight aggregate as recited in claim 1, wherein the expanded lightweight aggregate has a particle size comprising about 0-1 mm, 1-2 mm, 2-4 mm, 4-8 mm or a combination thereof.
 10. An expanded lightweight aggregate formed from a mixture comprising: a first ground glass or pumice in the range of about 40 to 60% by weight percent for a slurry; a water in the range of about 40 to 60% by weight percent for the slurry; a sodium silicate in the range of about 3 to 15% by weight percent for the slurry; a NaNO₃ in the range of about 0.1 to 5% for the slurry; a second ground glass or pumice in the range of about 50 to 85% by weight percent for a granulator; the slurry in the range of about 15 to 50% by weight percent for the granulator; and wherein the expanded lightweight aggregate has a bulk density in the range of about 0.10 to 0.5 g/cm³, an effective density in the range of about 0.10 to 0.8 g/cm³, a compressive strength in the range of about 0.5 MPa to 5 MPa, and a heat conductance in the range of about 0.04 to 0.15 W/mK.
 11. The expanded lightweight aggregate as recited in claim 10, wherein the water is in the range of about 45 to 50% by weight percent for the slurry.
 12. The expanded lightweight aggregate as recited in claim 10, wherein the sodium silicate is in the range of about 6 to 7% by weight percent.
 13. The expanded lightweight aggregate as recited in claim 10, wherein the NaNO₃ is in the range of about 0.9 to 1.1% by weight percent.
 14. The expanded lightweight aggregate as recited in claim 10, wherein the granulator has a ratio of about 1 part of the slurry to about 2.5 parts of the second ground glass or pumice.
 15. The expanded lightweight aggregate as recited in claim 10, wherein the expanded lightweight aggregate has a particle size comprising about 0-1 mm, 1-2 mm, 2-4 mm, 4-8 mm or a combination thereof.
 16. A method for manufacturing an expanded lightweight aggregate comprising the steps of: mixing a first ground glass or pumice in the range of about 40 to 60% by weight percent with water in the range of about 40 to 50% by weight percent to produce a slurry; adding a sodium silicate in the range of about 6 to 7% by weight percent to the slurry; adding a NaNO₃ in the range of about 0.9 to 1.1% to the slurry; forming aggregates in a granulator by feeding a second ground glass or pumice in the range of about 50 to 85% by weight percent with the slurry in the range of about 15 to 50% by weight percent; drying the formed aggregates; heating the dried aggregates together with a finely ground kaolin to a temperature of about 800 to 1400 degrees Celsius; and cooling the heated aggregates.
 17. The method as recited in claim 16, wherein the finely ground kaolin is about 30% by weight percent.
 18. The method as recited in claim 16, wherein the granulator has a ratio of 1 part of the slurry to about 2.5 parts of the second ground glass or pumice.
 19. The method as recited in claim 16, further comprising the step of grinding a glass or pumice in a ball mill to produce the first ground glass or pumice.
 20. The method as recited in claim 16, wherein the first ground glass or pumice has a diameter of predominately less than about 100 microns.
 21. The method as recited in claim 16, further comprising the step of dividing the cooled aggregates into one or more different end user size ranges.
 22. The method as recited in claim 16, further comprising the step of feeding the formed aggregates having a smaller size directly in to a flash drier that heats the formed aggregates above about 800 degrees Celsius to create aggregates in a size of about 0-1 mm.
 23. The method as recited in claim 16, wherein the expanded lightweight aggregate has a diameter of 0-8 mm, a bulk density in the range of about 0.10 to 0.5 g/cm³, a effective density in the range of about 0.10 to 0.8 g/cm³, a compressive strength in the range of about 0.5 MPa to 5 MPa, and a heat conductance in the range of about 0.04 to 0.15 W/mK.
 24. The method as recited in claim 16, wherein the expanded lightweight aggregate has a particle size comprising about 0-1 mm, 1-2 mm, 2-4 mm, 4-8 mm or a combination thereof. 